title: ANGPT2 promoter methylation is strongly associated with gene expression and prognosis in chronic lymphocytic leukemia.
abstract: Increasing evidence suggests a key role for angiopoietin-2 (ANGPT2) in influencing the aggressiveness of chronic lymphocytic leukemia (CLL). In the presence of vascular endothelial growth factor (VEGF), ANGPT2 causes vessel destabilization leading to neoangiogenesis. Accordingly, high expression levels of ANGPT2 and high degree of angiogenesis have consistently been associated with poor prognosis in CLL; however, the molecular mechanisms behind the variability in ANGPT2 expression are still to be discovered. Here, for the first time, we investigated the DNA methylation status of the ANGPT2 promoter in a large CLL cohort (n = 88) using pyrosequencing and correlated methylation data with ANGPT2 expression levels, prognostic factors and outcome. Importantly, methylation levels of the ANGPT2 gene correlated inversely with its mRNA expression levels (p<0.001). Moreover, low ANGPT2 methylation status was highly associated with adverse prognostic markers, shorter time to first treatment and overall survival. Finally, treatment with methyl inhibitors induced re-expression of ANGPT2 in two B-cell lymphoma cell lines, underscoring the importance of DNA methylation in regulating transcriptional silencing of this gene. In conclusion, we believe that the known variability in ANGPT2 expression among CLL patients could be explained by differential promoter DNA methylation and that low methylation levels of the ANGPT2 promoter have an adverse prognostic impact in CLL.
authors.affiliation: Hematology Unit, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Martinelli
authors.forename: Meena
authors.initials: M
authors.lastname: Kanduri
authors.forename: Rossana
authors.initials: R
authors.lastname: Maffei
authors.forename: Stefania
authors.initials: S
authors.lastname: Fiorcari
authors.forename: Jenny
authors.initials: J
authors.lastname: Bulgarelli
authors.forename: Roberto
authors.initials: R
authors.lastname: Marasca
authors.forename: Richard
authors.initials: R
authors.lastname: Rosenquist
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D042702:Angiopoietin-2 / Q000235:genetics*; D001483:Base Sequence; D015331:Cohort Studies; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D053208:Kaplan-Meier Estimate; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site; D001613:beta 2-Microglobulin / Q000235:genetics
chemical_list: C586513:ANGPT2 protein, human; D042702:Angiopoietin-2; D007143:Immunoglobulin Heavy Chains; D012333:RNA, Messenger; D001613:beta 2-Microglobulin
keywords: ANGPT2; chronic lymphocytic leukemia; gene methylation; prognosis; pyrosequencing